全文获取类型
收费全文 | 6387篇 |
免费 | 1篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 28篇 |
能源动力 | 1篇 |
轻工业 | 5篇 |
石油天然气 | 3篇 |
无线电 | 3篇 |
一般工业技术 | 6篇 |
冶金工业 | 6332篇 |
自动化技术 | 8篇 |
出版年
2019年 | 1篇 |
2017年 | 1篇 |
2011年 | 1篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 7篇 |
2003年 | 2篇 |
1999年 | 179篇 |
1998年 | 2021篇 |
1997年 | 1130篇 |
1996年 | 726篇 |
1995年 | 370篇 |
1994年 | 327篇 |
1993年 | 385篇 |
1992年 | 41篇 |
1991年 | 93篇 |
1990年 | 68篇 |
1989年 | 77篇 |
1988年 | 76篇 |
1987年 | 84篇 |
1986年 | 72篇 |
1985年 | 69篇 |
1984年 | 3篇 |
1983年 | 12篇 |
1982年 | 34篇 |
1981年 | 44篇 |
1980年 | 38篇 |
1979年 | 2篇 |
1978年 | 17篇 |
1977年 | 158篇 |
1976年 | 317篇 |
1975年 | 13篇 |
1965年 | 1篇 |
1955年 | 7篇 |
排序方式: 共有6388条查询结果,搜索用时 15 毫秒
991.
992.
993.
J Haan C Van Broeckhoven CM van Duijn E Voorhoeve F van Harskamp JC van Swieten ML Maat-Schieman RA Roos E Bakker 《Canadian Metallurgical Quarterly》1994,36(3):434-437
In 31 symptomatic and 5 asymptomatic carriers of the amyloid precursor protein (APP) gene codon 693 mutation, 10 family members without mutation, and 5 carriers of the APP gene codon 692 mutation (3 with early-onset Alzheimer dementia, 2 with cerebral hemorrhage), a high frequency of the apolipoprotein E epsilon 4 allele was found. Age at onset, age at death, occurrence of dementia, and number of strokes did not differ between APP gene mutation carriers with or without epsilon 4 allele, showing that the clinical expression of these APP mutations is not influenced by the apolipoprotein E gene. 相似文献
994.
995.
996.
We have measured haemodynamic responses to induction of anaesthesia, laryngoscopy and intubation in 103 mild-moderate hypertensive patients (83 patients (diastolic pressures < or = 110 mm Hg) currently receiving one of four monotherapies (ACE inhibitors, group A; beta adrenoceptor blocking drugs, group B; calcium channel antagonists, group C; diuretics, group D) and 24 were untreated hypertensive patients). Anaesthesia was induced with fentanyl 1.5-2.0 micrograms kg-1 and thiopentone 3-5 mg kg-1. Tracheal intubation was facilitated by vecuronium 0.1 mg kg-1 and anaesthesia maintained with enflurane and nitrous oxide in oxygen. Systolic and diastolic pressures (SAP, DAP) were measured at 1-min intervals by a non-invasive oscillometric method and cardiac output (CO) and stroke volume (SV) by thoracic bioimpedance. Induction of anaesthesia was associated with a decrease in SAP, DAP and CO in groups A-D (P < 0.05). Heart rate (HR) decreased in groups A and D (P < 0.01) and systemic vascular resistance (SVR) decreased in groups A and B (P < 0.05). SAP and HR increased in all groups after laryngoscopy and intubation (P < 0.01) as did SVR in groups A, B and D (P < 0.02). CO was unaltered. Similar changes occurred in the untreated hypertensive patients, although nine of 24 patients exhibited HR > or = 100 beat min-1 after laryngoscopy and intubation. Comparison of the changes in SAP, DAP, CO and SVR with time showed no differences in the five treatment groups; changes in HR were significantly less in group B compared with the other groups (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献
997.
We report the first molecular evolutionary analysis of the family Camelidae by analysing the full DNA sequence of the mitochondrial cytochrome b gene. Estimates for the time of divergence of the Old World (Camelini) and New World (Lamini) tribes obtained from sequence data are in agreement with those derived from the fossil record. The DNA sequence data were also used to test current hypotheses concerning the ancestors of the domesticated llama and alpaca. The results show that hybridization has occurred in the ancestry of both domesticated camelids, obscuring the origin of the domestic species. 相似文献
998.
AB Santos JC Ballenger JJ Bevilacqua JJ Zealberg TG Hiers S McLeod-Bryant PA Deci LJ Rames 《Canadian Metallurgical Quarterly》1994,151(8):1181-1187
OBJECTIVE: The authors discuss obstacles and incentives associated with successful community-based public-academic liaison activities and illustrate their conclusions by describing their public-academic liaison program, which received the American College of Psychiatrists' first annual Award for Creativity in Psychiatric Education. METHOD: The first 8 years of a state/university collaboration are described in which the parties involved first developed a variety of innovative services designed to fill specific gaps in the public service delivery system and subsequently integrated academic research and training components. RESULTS: The carefully planned and monitored process resulted in the exponential growth of interest in public sector work, the realization of the university's primary goals of developing high quality training and research sites, a substantial increase in the number of graduates accepting positions in the public sector, several projects funded by the National Institute of Mental Health, and two national awards. CONCLUSIONS: These collaborations illustrate the highly complementary relationship of public-academic liaison activities and their potential capacity to improve access to services, substantially improve the quality of these services, generate extramural support for services research, and increase the number of well-trained professionals in the public sector. 相似文献
999.
1000.